<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //1男，非1不是男
        var gender = prompt("请输入一个数");
        if ( gender.length > 1) {
            alert("不是男");
        } else {
            if ( gender == 1 ){
            alert("男");
            } else {
                alert("不是男");
            }
        }
    </script>
</body>
</html>